Generally speaking, and with all other things being equal, the efficiency of operation of a gas turbine increases as the turbine inlet temperature, that is, the temperature of the gas applied to the turbine blades, is increased. However, in practice some efficiency to be gained by high temperature operation is given up by using turbine inlet temperatures that are sufficiently low as to enable the turbine rotor to last a reasonable useful life without failure. In short, relatively higher turbine inlet temperatures, while increasing turbine efficiency decrease the useful life of the turbine while relatively lower turbine inlet temperatures provide for a long lived turbine, they result in decreased operating efficiencies.
In order to increase turbine life or allow turbine operation at higher turbine inlet temperatures without sacrificing useful life, various schemes have been proposed for cooling the turbine rotor. A number of the turbine rotor cooling schemes proposed are unwieldy and expensive to implement and thus have not been altogether satisfactory.
The present invention is directed to overcoming this difficulty.